Distribution of multiple pesticide residues in apple segments after home processing

Abstract

The effects of washing, storing, boiling, peeling, coring and juicing on pesticide residue were investigated for field-sprayed Discovery and Jonagold apples. Residues of chlorpyrifos, cypermethrin, deltamethrin, diazinon, endosulfan, endosulfan sulfate, fenitrothion, fenpropathrin, iprodione, kresoxim-methyl, lambda-cyhalothrin, quinalphos, tolylfluanid and vinclozolin in the processed apples were analysed by gas chromatography. Statistical analysis showed that reductions of 18–38% were required to obtain significant effects of processing practices, depending on pesticide and apple variety. Juicing and peeling the apples significantly reduced all pesticide residues. In the case of detectable pesticide residues, 1–24% were distributed in the juice and in the peeled apple. None of the pesticide residues was significantly reduced when the apples were subject to simple washing or coring. Storing significantly reduced five of the pesticide residues: diazinon, chlorpyrifos, fenitrothion, kresoxim-methyl and tolylfluanid, by 25–69%. Residues of the metabolite endosulfan sulfate were increased by 34% during storage. Boiling significantly reduced residues of fenitrothion and tolylfluanid by 32 and 81%, respectively. Only a few of the observed effects of processing could be explained by the physical or chemical characteristics of the pesticides. No differences in effect of processing due to apple variety were identified.

Keywords:

• pesticide residues
• home processing
• apple
• Discovery
• Jonagold

Notes

¹ Value supplied by Chemfinder (2002).

^† Spraying solution with the pesticides dissolved in 300 l water ha⁻¹.

^‡ Not a commercial product, but a test formulation obtained from a pesticide manufacturer.

^§ Value supplied by Syracuse Research Corporation (2002). Applied pesticide dose in the field trial per spraying (g active ingredients ha⁻¹), pesticide category, n-octanol–water-partitioning coefficient (K _ow) and vapour pressure (VP) (Tomlin 2000).

^† The RSD was calculated from the observations as the standard deviation (s) divided by the mean (m) and multiplied by 100%.

^‡ Extracted samples were diluted (1:11) by ethyl acetate:cyclohexane (1:1). Data are percentages.

^† Diazinon was not applied to Discovery apples and quinalphos was not applied to Jonagold apples. Significant effects of home processing on the residue in a specific processing compared with unprocessed apples are marked by single ( p<0.05) and double ( p<0.01) asterisks. A negative reduction represents an increase in pesticide residue compared with the unprocessed apples.

^† Diazinon was not applied to Discovery apples and quinalphos was not applied to Jonagold apples.

^† Calculated by applying Fisher's least significant difference (t-test) to the experimental log-normal transformed datasets.

^‡ Input data consisted of log-normal transformed mean pesticide residue concentration from 11 treatments in five replicates.

^§ Input data; log-normal transformed mean pesticide residue concentration from four treatments in five replicates.

^¶ Values are missing since the pesticides were not applied to this apple variety.